This Project focuses on the range of male-female mortality differences. The World Health Organization announced in 2006 that, for humans, female life expectancy exceeded the male level in all the world's countries. It is sometimes thought that this was always the case and that the gap is roughly the same across countries. Furthermore, it is sometimes asserted that female life expectancies exceed male levels for almost all species. The truth is more complicated. The research in this Project relies on lifetables that can be found in the literature and on websites or that we propose to estimate. The lifetables will be analyzed to document the range of male-female mortality differences across human populations over time and place. The Project will also document the range of male-female mortality differences in nonhuman vertebrates by using and analyzing sex-specific mortality data for about 600 species of vertebrates (i.e., mammals, birds, reptiles, amphibians and fish). It includes: (1) An analysis of about 3,000 pairs of sex-specific lifetables for human populations over the past 250 years. This will shed new light on the range of differences between male and female life expectancies as well as on male-female age-specific death rates and identify the populations with the biggest and smallest differences. Factors contributing to the gaps will be investigated. (2) A re-assessment of skeletal age-at-death data and an estimation of lifetables for human experience over the past 10,000 years. With this new (re-assessed) data, we will test the hypothesis that from the Neolithic until the late Middle Ages male life expectancy was higher than female life expectancy. Together with the findings from our analyses of human lifetables (see above), these findings will be of importance in providing a better understanding of the development of human male-female longevity differences. (3) A study of sex-specific lifetables and life-expectancies for some 600 vertebrate species. This will reveal the range of the relative life-expectancy gap across species of mammals, birds, reptiles, amphibians, and fish and not only show how universal the purported female advantage is, but also shed new light on the species characteristics that determine the size of the gap. RELEVANCE (See instructions): Is it true that males are healthier than females but die younger? If so, why? This research Project addresses these questions concerning the human health-survival paradox. Findings will provide a deeper understanding of the basis for sex differences in health and survival and of the opportunities that society and particularly health professionals have to improve health and survival for males and females.